The present invention relates in general to the sealing of a confined cavity, defined by the inside of a hollow structure, which itself consists of a mechanical assembly of several parts, subassemblies or components, the said structure moreover having a defined function or role, as it belongs to an apparatus or device or machine.
As an example, but not in a limiting manner, the present invention will be introduced, defined and explained with reference to aircraft, including transport planes, and to any fuel tank incorporated into the structure of the said aircraft in the following manner:                to save weight or space, all or some of the tanks required for storing fuel are obtained using the confined volume(s) of one or more hollow structures, for example those belonging to the wings, in order to contain the stored fuel directly;        for this purpose, the line or the various lines joining the parts of the structure defining the confined volume that forms a tank, which are liable to form respectively one or more leak lines to the outside of the hollow structure used for storing the fuel, are sealed with any bonding material or seal having the required characteristics, both mechanical and sealing characteristics, in order to directly obtain the desired tank in the hollow structure used for this purpose.        
The term “sealing” is understood to mean both the original sealing of the hollow structure, that is to say at the time of its construction, including assembly, and subsequent sealing, for example for carrying out maintenance, including repair, on this same hollow structure.
The present invention relates more particularly, but not exclusively, to the sealing of a hollow structure as defined above, for example an aircraft tank, for the purpose of repairing it.
When repairing an aircraft tank, consisting of a hollow structure, for example in its wing, this very often entails having to seal the entire leak line to the outside of the hollow structure, identified beforehand and located as to its position and its extension, for example with the aid of the aircraft construction drawings.